write local consensus state when witness feature is enabled

solana/solana-ibc/programs/solana-ibc/src/lib.rs

@@ -402,11 +402,26 @@ pub mod solana_ibc {
         let height = store.borrow().chain.head()?.block_height;
         // height just before the data is added to the trie.
         msg!("Current Block height {}", height);
+        let previous_root = store.borrow().provable.hash().clone();
 
         ::ibc::core::entrypoint::dispatch(&mut store, &mut router, message)
             .map_err(error::Error::ContextError)
             .map_err(move |err| error!((&err)))?;
 
+        #[cfg(feature = "witness")]
+        {
+            let root = store.borrow().provable.hash().clone();
+            if previous_root != root {
+                msg!("Writing local consensus state");
+                let slot = Clock::get()?.slot;
+                let timestamp = Clock::get()?.unix_timestamp as u64;
+                let storage = &mut store.borrow_mut().private;
+                storage
+                    .add_local_consensus_state(slot, timestamp, root)
+                    .unwrap();
+            }
+        }
+
         Ok(())
     }
 

solana/solana-ibc/programs/solana-ibc/src/storage.rs

@@ -1,6 +1,8 @@
 use alloc::rc::Rc;
 use core::cell::RefCell;
 use core::num::NonZeroU64;
+#[cfg(feature = "witness")]
+use std::collections::VecDeque;
 
 use anchor_lang::prelude::*;
 use borsh::maybestd::io;
@@ -313,6 +315,9 @@ pub struct PrivateStorage {
 
     // Fee to be charged for each transfer
     pub fee_in_lamports: u64,
+
+    #[cfg(feature = "witness")]
+    pub local_consensus_state: VecDeque<(u64, u64, CryptoHash)>,
 }
 
 #[derive(Clone, Debug, borsh::BorshSerialize, borsh::BorshDeserialize)]
@@ -387,6 +392,20 @@ impl PrivateStorage {
                 client_id: client_id.clone(),
             })
     }
+
+    #[cfg(feature = "witness")]
+    pub fn add_local_consensus_state(
+        &mut self,
+        slot: u64,
+        timestamp: u64,
+        trie_root: CryptoHash,
+    ) -> Result<(), ibc::ClientError> {
+        if self.local_consensus_state.len() == MAX_CONSENSUS_STATES {
+            self.local_consensus_state.pop_front();
+        }
+        self.local_consensus_state.push_back((slot, timestamp, trie_root));
+        Ok(())
+    }
 }
 
 /// Provable storage, i.e. the trie, held in an account.